Fluid pressure brake



M 1935. 11.1. ALDRIDGE ,986,460

FLUID PRESSURE BRAKE Filed May 27, 1931 INVENTOR. THOMAS J. ALDRIDGE ATTORNEY.

l ineiTecting-anapplicationof'the brakes is 'ar-' thereto.

Patented Jan. 1,1935 I l 9 e V g FLUID'P ESSURE BRAKE Thomas l-"Turin, Italy, assignor to The Westinghouse" AirljBrake Company, Wilmer- V ding; Pa a corporation of Pennsylvania l Application Mayiw; 1931, Serial No.'540,'246 1 v t t 1: I n (ireat'tBritain July 22, 1930 t w r o ini. (o1; sot-84) This invention relates to valves'adapted to be fluid to effect an actuaireduction in the efifective actuated by fluid underpressure for thepurp'ose pressure exerted upon the abutment tending to of controllingv the supply of fluid in accordance close ortoperinit the closing of-thewalve. The with the pressure conditions obtaining in the movement or the-abutment for this purpose will 5. space orreceptaclesupplied with fluid through. thus only occur under'the =action oi the static 5f the valve-and hasiorits object toprovideejrr fluid pressure obtainingin' the receptacle and is improved controlling valve of this character." thus rendered independent or sudden'variations The invention may beapplied tovalve devices in pressure. r i p actuatedby fiuid'under pressure for various' pur- In the accompanying drawingz Fig. 1 is a view 1 0 poses and is particularly"applicebleto the soor a fluid pressure car brake equipment, showing calledquick-inshofivalves employed inconnec the triple valve devicein section, with" my imtion withthe triplefior distributing valves o'ffiuid provement embodied therein; and Fig. 2 a secpressure braking apparatus in which the supply tional view oi Ian inshot valve device with a ofiluid tothe brake' cylinder oi the apparatus slightly modified for-moi my invention applied ranged to occur in two distinct stages determined "The brake equipment j shown in Fig. i com byfthe action off-the quick-inshot valve; This prises a triple valve device 25 having a piston valve is interposed in the patlicfthe iluid-"iiow-i chamber 26 connected to the usual brake pipe 2'? ing from theservice port or thetriple valve slide and containing piston "28 and having a valve valve tothe passage'leading tothe brake cylinf chamber 29, connected to the usual auxiliary- 1 struc'ted, itisioundtliat some cases -the ow der, the valvebeingnoi mally openandbeirigar reservoir 30 and containing a main slide valve rangedto be closed; as soonasa predetermined 31 and a graduating "slide valve- 32 adapted to pressure is obtained in the-brake cylinderg;the be operated by piston 28. i

closing of the valve under these gconditions'beijrjg 'Associated'with the' triple valve device efi'ect-ed or permitted byfithe "actionnfjthe brake an inshot valve device comprising a casing 1 con- 25 cylinder pressure acting upon an abutment in tainin'g a ball valvez'adapted in its closed posi- I opposition to a spring oi fits" equivalent normally tion to engage with a'suitablevalve seat 3, a chamtending to maintain the valve ope er' the be'r 4'above whichl'eads 'througba-passage 5 to valve has been closed in this'inanner, he the! the service porter the dis'tributing or triple valve" y supply of fluid under pressuret'fthe brake eylindevice '25; 'A small chamber "6 formed underneath der is tn'ranged to occur a more restricted the valve seat 3 leads to a suitable passage loommun ioatingwith the"brake-cylinder 33 and the ball va1ve=2 is arranged normally to be held away j from-its seat 3 so as to provide relatively unremanner through a by- 'pass or predetermined suit" able capacity;

In valves or this c aracter as usiieii" i of air through the -val've"before' its closure fig and thecharnberfi by meansof a stem 8 project- "liable to exert a pres ure oiithe abutment'flabbve in verti a ly upward o a is o 9 ad p d referred'to, which is, owing t'othe rate btfilow to movein a vertical cylinder provided in the -of the air, greater thanfthat corresponding to lower p f th casing 1. The piston Q'isnorf the actual pressure obtaining in thebrake oyl'in der for the'timebeing',with' the resuitthatehe sh wn hth draw n y m ans a spr n 10 v l te ds t dos prematurely and havingactingon the under sideof the piston 9, the stem thus closed, thejiiuid pressureyaenng on the= 8 projecfihgthrough b e pe e 11 in i butm nt 1S ed d t dm xtnt,- sw ng t the base.12of the lowerchamber 6, so as to en- 4 the reduction in the rate-offlowjwiththe resale gage with the ball valve 2 and hold the latter is;

' that the valve tends toreopen. The effectofthis awayircm its seat 3. The upper face of the actionis thus to 'preVent-the closing movement piston 9 is provided with-anannular gasket 13 of the valve from occurring in the desired posiadaptedto engage witha corresponding annular tive, definite and final manner when the prerib 14 formed in the upper end of the cylinder,

50 determined brake cylinder pressure is obtained. so thatwhen the piston 9 is in its uppermost po- 50 According to the present invention this dissition, that portion only of the upper face of the advantage is obviated by providing arrangements piston 9 lying within the annular rib 14 is subject for protecting the abutment from fluidpressure to the pressurein the W Chamber 6 nd 0011- due to the flow of fluid through the open valve sequently to the brake cylinder pressure. The

5 or adjacent thereto or by causing the flow of the chamber 4 above the valve seat 3 and the lower 55 stricted communication between the chamber 4 mally; maintained in its uppermost position chamber 6 are arranged to communicate with one another through a restricted port or aperture 15, forming a by-pass to the valve, and it will be understood that when fluid is first supplied through the service port of the distributing valve and pas- .sage 5 to the chamber 4, this fluid flows freely past the ball valve 2 to the lower chamber 6 and thence to thebrake cylinder 33 throughthe passage 7. When a predetermined pressure is obtained in the brake cylinder, this pressure acting upon the central portion of the upper face of the piston 9 inside the rib 14 causes the piston to move downwards and to permit the ball valve 2 to move downwards on to its seat 3,,the subsequent supply of fluid to the brakecylinder occurring through the restricted Icy-pass port 15. Owing to the provision of the annular rib 14, the

initial downward movement of the piston 9 causes the mannerabove explained, is effected by the clearance between the stem 8 of the piston and the aperture in the base 12 of the, lower chamber 6 through which the stem 8 passes. It is found in practice, however, that the fluid flowing past the open ball valve isliable to exert, due to its rate of flow, a pressure uponthe upper face of the piston 9 which is in excess 'of that due to the actual static conditions in the lower chamber 6 and in the brake cylinder, and in the construction shown in Figure 1, this undesirable action is prevented by causing the stem 8 of the piston 9 when the latter is in its upper position to fit within the aperture 11 leading from the lowerchamher 6 to the upper face ofthe piston 9 with the minimumclearance necessary for eifective operation. I j j V 7 In other words,-the stem 8. isarranged toqcut off as completely as possible direct'communica tion between the lower chamber 6 and the u per. face of the piston 9, this communication being on the other hand {established througha port or orifice 16 whichisas remote asipossible from the direct pathof flow of air past the ballvalveZ,

In the construction'shown in Figure 2 the port or orifice l6 establishing communication between the lower chamber 6 and the upper face of the piston 9 is inclined from the vertical so as *to be nearly parallel to the general direction of the flow of fluid in the passage 7 leading to the brake cylinder, the opening or mouth 17 of :this passage leading into the lower chamber 6ror into the brake cylinder passage '7, being so formed that the flowv of air to the brake cylinder will cause byejector action a positive reduction in the pressure exerted upon the upper face of the piston 9 solong as unrestricted flow of air to the brake cylinder continues. By this arrangement the pressure exerted upon the upper face of thepiston 9 may be renderedsomewhat less than that due to the static pressure of the fluid flowing to the brake cylinder and the opening movement of the piston 9 will consequently be delayed until the rate of flow of fluid has been reduced to an extent sufiicient to permit the developmentof a static fluid pressure on the upper face of the piston sufiicient to overcome the action of the controlling spring 10.

As shown in Figure 2,,the lower, part 18 of the stem 8' only maybe arranged to jfltplosely into the aperture 11 leading fr'om'the lower chamber 6 to the space above the piston 9, the remaining portion'of the stem 8 being of such dimensions as to permit relatively free communication between the lower chamber 6 and the piston 9.

In another construction the piston stem 8 may, as shown in 'Figure 1, be of such form as to permit a gradually increasing clearance or freedom of communication between the lower chamber 6 and the upper face of piston 9 as the latter moves downwards.

The increase in the freedom of communication between the chamber 6 and the space abovethe uppersurface of the piston 9 which occurs in both constructions, butmore particularly in the construction of Figure 2 as above explained when the piston 9 commences to move downwards, pos-,

sesses the important advantage of preventing any momentary lag or. halt in the movement of the piston-9 due to the sudden expansion. of the fluid within the annular rib-l4 when the-gasket 13' moves out of engagement therewith. The temporary reduction in pressure'on the piston due to.

this expansion is thus compensatedfor by the relatively free flow of, fluidfrom thechamber 6; as soon as the piston begins; to move andthis movement is thus rendered;.;positive-. and continuous. v

, The invention is idnuyfndt limited. in its application to fluid pressure-braking apparatus;

but may be employed in connection with pressure actuated valves for other purposes in .which a positive and definite action of the valveis required when a predetermined fluid ,pressure is fluid from the valve.

obtained in the space or receptacle supplied with.

' Furthermore, the inventioniisnot limited as appled to fluid pressure-braking apparatus to any of the particular constructions-above described and illustrated by way of example.

, Hav: g now particularly de cr bed and ascertained'the nature of the said-invention andin what manner the same-is to be" performed, I;

declare that whatIclaimjs: 1

In a fluid pressure brake, the combination with a brake cylinder, of avalve device forregulating the rate of flow of fluidunder pressure to.

the brake cylinder, comprising a valve for controlling the flow of fluidtothe-brake cylinder, a'

movable abutment normally maintainingsaid valve in open position and operated upon a predetermined increase in:the pressure-of fluidflowing to'the brake cylinder pressureto permit said valve to seat, said valve device having a restrictedport for supplying fluid to said-abutment, and means'operated by the flow of fluid to the brake cylinder for reducing the pressure of fluidon said abutment. 

